1. Field of the Invention
The present invention relates to a lens barrier device of an imaging apparatus such as a video camera or a digital camera.
2. Description of the Related Art
A conventional lens barrier device has the following construction (See, for example, Japanese Patent Application Laid-Open No. 2010-156732). In the following, the construction will be described with reference to FIG. 12. In this conventional example, to protect an imaging lens, four barrier blades in total, i.e., outer barrier blades 120a and 120b, and inner barrier blades 130a and 130b, rotate around rotation shafts 112a and 112b parallel to the optical axis of an imaging lens provided in an external cover 110.
As illustrated in FIG. 13, when the lens barrier device is in the open state, the outer barrier blade 120a and the inner barrier blade 130a, and the outer barrier blade 120b and the inner barrier blade 130b, are respectively overlapped one upon the other in the optical axis direction. With this construction, the projection area as seen from the optical axis forward end side in the open state is reduced, thereby realizing a reduction in the diameter of the imaging lens of the imaging apparatus.
However, in the above described conventional technique, the external cover 110 is assembled to the imaging apparatus main body in combination with some other external cover, and the like. Thus, deformation due to the assembling is generated in the external cover 110. As a result, the rotation shafts 112a and 112b undergo deformation, and the requisite driving force for the opening/closing operation increases. As a result, a proper opening/closing operation is hindered.
On the other hand, if an attempt is made to realize in the external cover 110 a configuration preventing deformation due to the assembling to the imaging apparatus main body, there is involved a limitation to the configuration of the external cover arranged in front of the imaging apparatus main body. This is not desirable since it leads to a limitation in terms of salability such as design.
In view of this, there has been formed a lens barrier unit by additionally providing another member having the rotation shafts 112a and 112b between the external cover 110, and the outer barrier blades 120a and 120b. This configuration is generally used for a lens barrier device of a construction with the above-mentioned lens barrier unit fixed to the external cover.
This makes it possible to suppress the deformation due to the assembling of the external cover. However, this involves an increase in the number of components, resulting in an increase in the production cost of the imaging apparatus main body, and an increase in the size in the optical axis direction of the apparatus due to the additional components.